BackgroundTo evaluate the occurrence of malnutrition in pulmonary embolism (PE)-related hospitalisations and assess the impact of malnutrition on the outcomes of patients with PE.MethodsA retrospective observational study using data extracted from the Nationwide Inpatient Sample from 2016 to 2018. Hospitalisations with a principal diagnosis of PE were obtained using International Classification of Diseases, Tenth Revision codes and divided into groups based on a secondary diagnosis of malnutrition.ResultsOf 563 135 PE hospitalisations, 30 495 (5.4%) had malnutrition. PE patients with malnutrition were older (mean age±SD, 69.1±14.5 vs 62.3±16.6, p<0.001) and with higher Charlson Comorbidity Index score (3 to 5, 24.8% vs 12.9%, p<0.001). Concurrent malnutrition was associated with higher adjusted OR (aOR) of in-hospital mortality (aOR 2.43, 95% CI 2.18 to 2.70, p<0.001), acute kidney injury (aOR 1.56, 95% CI 1.45 to 1.67, p<0.001), sepsis (aOR 4.37, 95% CI 3.79 to 5.03, p<0.001), shock (aOR 2.52, 95% CI 2.25 to 2.81, p<0.001), acidosis (aOR 2.55, 95% CI 2.34 to 2.77, p<0.001) and mechanical ventilation (aOR 2.95, 95% CI 2.61 to 3.33, p<0.001). Patients with PE and malnutrition had an increased mean length of stay (adjusted difference 3.39 days, 95% CI 3.14 to 3.65, p<0.001), hospital charges (adjusted difference US$34 802.11, 95% CI US$31 005.01 to US$38 599.22, p<0.001) and costs (adjusted difference US$8 332.01, 95% CI US$7489.09 to US$9174.94, p<0.001).ConclusionConcurrent PE and malnutrition were associated with worse outcomes. The study highlights the importance of identifying malnutrition in patients with PE to improve outcomes and reduce healthcare utilisation.